Cant believe she wont call her family. did you ask for their phone numbers? Not that it wouldnt serve that family right if you did that but you also dont want it to ruin your friend's shower. His family might be the type to make a big deal over something like that, even though its really their faults for not RSVPing. I
I like Amarillis' suggestion.
Do you have anyone else on his side that's in the bridal party? like does he have a sister or anything that you can designate that as their job. It's pretty crappy if your making the food too, that's a lot of work for people who cant bother to let you know your going.